Energy and Energy Resources
Energy Defined as the ability to do work or the ability to cause change.
Two types of energy: Kinetic energy- energy of motion; anything that moves has kinetic energy, cars, balls, and even atoms. Potential energy- stored energy; sometimes called energy of position, anything not moving has potential energy
Swinging Pendulum P.E. is greatest here, K.E. = 0 P.E. is greatest here, K.E. = 0 Kinetic energy is greatest here, P.E. =0
Kinetic energy The amount of kinetic energy an object has depends on two things: 1. mass 2. velocity K.E. = 1/2mv ½ (mass X velocity squared) 2
Potential Energy This is the energy that something that is not moving has the potential of having. Potential energy depends on: 1. mass 2. position (height and gravity) P.E. = mgh (mass X gravity X height)
Forms of energy Thermal Chemical Light Sound Electrical Nuclear All forms of energy have kinetic and/or potential energy.
Thermal energy Heat energy- all objects have thermal energy; it increases as temperature increases. Which has more thermal energy? Why?
Chemical Energy Energy stored in chemical bonds; includes the food we eat.
Light energy Form of energy that we see.
Sound energy Energy caused by vibrations; some of these vibrations we can hear.
Electrical energy Energy that is carried by an electric current (a path that electrons follow).
Nuclear Energy Energy from the nucleus of an atom
Energy Transformations Change from one form of energy to another. Always produces thermal energy (heat).
Examples of energy transformations Photosynthesis (light to chemical) Digestion of food (chemical to mechanical) Burning of fuel (chemical to mechanical and thermal) Electrical to light and thermal (light bulb)
Law of Conservation of Energy States that energy cannot be created or destroyed, only transferred or changed from one form to another.
Kinetic and Potential Energy Kinetic energy and potential energy can be transferred back and forth as seen in a swinging pendulum or throwing a ball up.
Transforming Chemical Energy Can be seen as chemical reactions occur in living things causing bonds to be broken and kinetic energy (contraction of a muscle) to be formed. Decomposition of dead or decaying matter.
Transforming Electrical Energy Electrical energy can be transformed to sound energy (listening to the radio) Electrical energy can be transformed to chemical energy (neurons fire and release chemicals)
Transforming Thermal Energy Thermal energy can be changed to mechanical energy (steam used to move locomotives) Thermal energy can be transformed to light (radiant) energy (glowing metal on stove)
Generating Electrical Energy Generator- device that transforms kinetic energy into electrical energy Turbines- set of steam powered fan blades that spins a generator at a power plant.
Chemical Energy of Coal Electric Power Plants Power plants- most power plants use energy from coal to start the transformation of energy similar to below. Thermal Energy of Water Kinetic Energy of Steam Kinetic energy Of turbine Electrical Energy
Sources of Energy Energy that we use comes from two main sources: 1. Renewable resources- resources that can be replaced 2. Nonrenewable resources- resources that cannot be replaced
Nonrenewable Resources Fossil Fuels- formed from the remains of once living things. - energy from these can be traced back to the sun through the food chain
Fossil Fuels- there are three main types of fossil fuels Coal- formed from the remains of plants that once lived on land Petroleum-(crude oil) formed from the remains of microscopic organisms in the oceans. Natural gas- sometimes found along with deposits of petroleum; also formed from ancient ocean microscopic life
Coal Primarily used for generating electricity; also used for paper production and iron and steel production. Coal is mined from deposits in two methods: Surface mining Underground minin
Petroleum Refining petroleum produces gasoline, kerosene, asphalt and petrochemical products such as plastics; some perfumes and insecticides are made from products of crude oil
Natural gas (methane) Natural gas is used to heat ( and in some cases cool) homes and other buildings; also used for generating electricity Burns the cleanest of the fossil fuels Can be produced- (by-product of decaying organic matter)
What s so bad about these fossil fuels? 1. Energy crisis result of over dependence on fossil fuels 2. Burning fossil fuels releases sulfur dioxide which mixes with rain and causes acid rain 3. Burning fossil fuels also releases carbon dioxide which contributes to the greenhouse effect
Nuclear energy Energy from fission (splitting of the atom) can be converted to other sources of energy such as electricity Negatives- produces radiation that has to be contained; Uranium is nonrenewable
Renewable Resources Solar energy Geothermal energy Tidal energy Wind energy Hydroelectric energy Biomass
Solar energy- energy from the sun Collected by thermal collectors (roofs) or photovoltaic cells (calculators, roofs, satellites)
Geothermal energy- heat from deep inside the earth is used as an energy source
Wind energy- windmills convert kinetic energy to electrical energy
Hydroelectric energy Water that is behind a dam can be used to move turbines and generate electricity.
Tidal energy Energy from the ocean tides can be used to generate electricity.
Biomass Energy from living things (primarily plants) can be used for fuel.